A gas turbine generally includes a compressor which generates compressed air by compressing ambient air, a combustor which generates combustion gas by mixing fuel into the compressed air and burning the mixture gas, and a turbine having a rotor which is rotated by the combustion gas. The combustion gas having rotated the rotor of the turbine is discharged into the atmosphere through an exhaust chamber of the turbine.
In such a gas turbine, with increases in efficiency, the temperature of the combustion gas which is supplied to the turbine is becoming extremely high. For this reason, a lot of components of the turbine have become objects to be cooled, and components constituting the exhaust chamber or components around the exhaust chamber have also become objects to be cooled.
A cooling structure around the exhaust chamber in a gas turbine is disclosed, for example, in Patent Document 1 below. The exhaust chamber is formed with a cylindrical exhaust chamber wall around a rotation axis of a rotor. Cylindrical outer and inner diffusers are arranged on the inside of the exhaust chamber wall in the radial direction around the rotation axis of the rotor. The outer diffuser is provided along the inner periphery of an exhaust chamber wall. The inner diffuser is arranged inside the outer diffuser in the radial direction with a space therebetween. A space between the outer diffuser and the inner diffuser forms a combustion gas exhaust air channel. In addition, a bearing which rotatably supports the rotor, and a bearing housing which covers and supports the bearing are provided on the inside of the inner diffuser in the radial direction. The exhaust chamber wall and the bearing housing are connected to each other by a strut which passes through the outer diffuser and the inner diffuser. The strut extends in the tangential direction of the rotor, and is covered by a strut cover along the extending direction thereof. One end of the strut cover in the extending direction is attached to the outer diffuser, and the other end is attached to the inner diffuser. A partitioning wall having a strut through-hole through which the strut passes is arranged between the inside of the inner diffuser in the radial direction and the outside of the bearing housing in the radial direction.
For example, compressed air which is extracted from the compressor is supplied as cooling air to a space between the inner periphery of the exhaust chamber wall and the outer periphery of the outer diffuser. The cooling air passes through a gap between the strut and the strut cover, flows into between the inner periphery of the inner diffuser and the partitioning wall, and is then discharged into the combustion gas exhaust air channel, for example. During this time, the cooling air cools the outer diffuser, the strut, the strut cover, and the inner diffuser.
The upstream side portion of the partitioning wall and the bearing housing are sealed therebetween so that the partitioning wall is movable relative to the bearing housing in the axial direction and the radial direction. In addition, the downstream side portion of the partitioning wall and the inner diffuser are sealed therebetween so that the partitioning wall is movable relative to the inner diffuser in the axial direction and the radial direction.
A partitioning wall support member which supports the partitioning wall, which is relatively movable with respect to the bearing housing and the inner diffuser in the axial direction and the radial direction, is provided between the partitioning wall and the bearing housing. The partitioning wall support member includes a cylindrical outer support member of which an outer end in the radial direction is fixed along an edge of a strut hole of the partitioning wall, and which covers the strut, and a cylindrical inner support member of which an inner end in the radial direction is fixed to the bearing housing and which covers the strut. The outer support member is movable in the extending direction of the strut relative to the inner support member, and a seal member which seals a gap between the support members is arranged therebetween.
That is, in the gas turbine disclosed in Patent Document 1, cooling air, which flows from the inside of the strut cover to the inside of the inner diffuser in the radial direction, is sealed by the partitioning wall and the partitioning wall support member.
In the gas turbine disclosed in Patent Document 1, when the strut expands in the extending direction thereof due to its thermal expansion, the bearing housing is rotated around the rotation axis of the rotor since the extending direction is the tangential direction of the rotor. In this manner, when the bearing housing is rotated, the relative positions of the inner support member and the outer support member in the extending direction are changed. Therefore, as described above, in the gas turbine, the outer support member is movable in the extending direction relative to the inner support member.